Safety Data Sheets (SDS): How to Read Sections 2 and 3 for Flavors

Author: R&D Team, CUIGUAI Flavoring
Published by: Guangdong Unique Flavor Co., Ltd.
Last Updated: Sep 16, 2026
WhatsApp & Telegram: +86 189 2926 7983
Email: info@cuiguai.com

A Safety Data Sheet (SDS) is the 16-section technical document that travels with every hazardous chemical placed on the market. For e-liquid flavor concentrates — mixtures of aroma chemicals, solvents such as propylene glycol and vegetable glycerin, sweeteners, and cooling agents — the SDS is the single most important compliance document a brand owner, importer, or quality manager will ever receive from a supplier. The 16-section format comes from the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), and it is legally required in most major markets: in the United States under the OSHA Hazard Communication Standard (29 CFR 1910.1200), and in the European Union under the CLP Regulation (EC) No 1272/2008 together with Annex II of the REACH Regulation (EC) No 1907/2006.

Every one of the sixteen sections matters, but Sections 2 and 3 carry the most weight. Section 2 tells you what the hazard is; Section 3 tells you which ingredients cause it and at what concentration. Read together, they answer the questions that determine whether a flavor is safe to handle, ship, and formulate with: Is this concentrate flammable? Does it contain a skin sensitizer? Is the declared composition consistent with the classification on the label? This guide explains how to read these two sections for flavor compounds, what regulators actually require, and how to build a verification checklist that protects your brand.

Reading the SDS of a Flavor Concentrate: Sections 2 and 3

Why Sections 2 and 3 Determine Your Compliance Burden

A flavor concentrate is rarely a single substance. A typical product combines dozens of ingredients, and its hazard profile is a function of the whole mixture, not just the headline component. Under GHS-based rules, mixtures are classified by evaluating every ingredient that contributes to a hazard class above its concentration cut-off. That is why the classification in Section 2 and the composition in Section 3 must be mutually consistent. If Section 3 declares a high percentage of ethanol but Section 2 shows no flammable classification, the SDS is internally inconsistent — and that inconsistency is a red flag in any audit.

The stakes are practical. Carriers need the correct transport classification, warehouse staff need the correct storage conditions, and downstream users in the EU need the composition data to complete their own poison centre notifications and supply-chain communications. Buyers who cannot interpret Sections 2 and 3 routinely accept SDSs that understate flammability or omit sensitizers — problems that surface only after an incident, an inspection, or a rejected shipment. The same ingredient controls are at the heart of the EU TPD compliance requirements for e-liquid ingredients, which is why documentation literacy starts with these two sections.

Section 2 — Hazard(s) Identification

Section 2 is the hazard summary of the SDS. Under GHS, it must present the classification of the substance or mixture and the label elements that follow from it. OSHA describes the same content in Appendix D of the Hazard Communication Standard, and the CLP Regulation implements it in the EU with a slightly different set of hazard classes and category codes. Whatever the jurisdiction, the goal is identical: a reader should be able to look at Section 2 and immediately understand what the material can do.

The Six Blocks of a Compliant Section 2

A complete Section 2 contains six identifiable blocks:

1. Classification of the substance or mixture — the assigned hazard classes and categories, expressed with H-statements such as Flammable Liquid Category 2 (H225) or Skin Sensitiser Category 1 (H317).
2. Label elements — the signal word (only “Danger” or “Warning” exist in GHS), the applicable pictograms, the hazard statements (H-codes), and the precautionary statements (P-codes).
3. Other hazards that do not result in classification — for example, hazards not otherwise classified (HNOC) under US rules, or a “no additional information” placeholder used in many EU SDSs.

Some SDSs add a short narrative paragraph above these blocks. That narrative is useful context, but it is not regulatory content; the structured blocks are what an auditor checks.

How Flavor Concentrates Are Usually Classified

Flavor concentrates are classified across a predictable set of GHS hazard classes. The most common ones you will see on a flavor SDS are:

• Flammable liquids — concentrates with high percentages of ethanol or other alcohol solvents typically fall in Flammable Liquid Category 2 (H225) or Category 3 (H226), depending on flash point.
• Skin irritation and eye irritation — many aroma chemicals, including citral, cinnamaldehyde, and certain esters, trigger Skin Irritation Category 2 (H315) or Eye Irritation Category 2 (H319) at relevant concentrations.
• Skin sensitisation — cinnamaldehyde, eugenol, limonene, and other fragrance allergens are classified Skin Sensitiser Category 1 (H317) when present above the 0.1% CLP concentration threshold. This is one of the most frequently missed classifications in flavor SDSs.
• Acute toxicity — some ingredients, such as coumarin or benzyl alcohol, carry acute oral or inhalation toxicity classifications that flow into the mixture at low percentages.
• Aspiration hazard — low-viscosity solvent components can trigger Aspiration Hazard Category 1 (H304).
• Aquatic toxicity — concentrated spill material and unused waste are evaluated against environmental classes such as Aquatic Chronic Category 2 (H411) or Category 3 (H412).

The exact set depends on the formula. A menthol-heavy cooling system and a caramel-vanilla base can produce completely different Section 2 blocks, which is why classifications should never be copied from one product to another.

Label Elements You Must See

When a mixture is classified as hazardous, Section 2 must reproduce the label elements that will appear on the container. Check the signal word first: GHS recognizes only “Danger” and “Warning”. Then check the pictograms: GHS defines nine pictograms in total, although the environmental pictogram is not required under US HazCom labelling rules while it is required under EU CLP. Every pictogram shown must correspond to a declared hazard class. Finally, check that every H-statement has a matching set of P-statements covering prevention, response, storage, and disposal. A Section 2 that declares H317 without P280, P302+P352, P333+P313, and P362+P364 is incomplete on its face.

Other Hazards and Placeholder Text

Not everything that matters is a classified hazard. OSHA requires the SDS to state other hazards that do not result in classification, and EU SDSs often record “no data available” or “none known” in this subsection. For flavors, the more useful entries are process notes such as “may form flammable vapour-air mixtures above the flash point”. When the box is empty, read it as “the supplier did not evaluate this”, not as “there are no other hazards”.

Common Section 2 Failures in Flavor SDSs

• Understating flammability by reporting only the main solvent classification instead of the mixture classification.
• Omitting skin sensitisation even though the formula contains cinnamaldehyde, limonene, or eugenol above the relevant threshold.
• Listing H-codes without the corresponding P-codes.
• Using hazard statements that do not exist in GHS or CLP.
• Copying Section 2 from a previous formula after an ingredient change, leaving stale codes on the document.

Each of these failures can be caught in a ten-minute document review — provided you know what to look for.

SDS Section 2 Hazard Classification Explained for E-Liquid Flavors

Section 3 — Composition/Information on Ingredients

Section 3 is the ingredient declaration of the SDS. For a mixture, it must list the identity of every hazardous ingredient that contributes to the classification of the mixture, together with its CAS number and its concentration or concentration range. OSHA Appendix D requires the chemical identity and appropriate concentration data for all hazardous ingredients; REACH Annex II, Section 3, requires the same for ingredients that present a health or environmental hazard above the applicable concentration limits. The composition data in Section 3 is also the backbone of the ingredient controls that regulators verify during TPD compliance checks, so the two documents must tell the same story.

For a flavor concentrate, Section 3 typically lists the main solvents (propylene glycol, vegetable glycerin, ethanol), the high-volume aroma chemicals, and any sensitizer or toxicant present above the classification threshold. Ingredients below the threshold may be omitted, which is why Section 3 is never a complete recipe — it is a hazard-relevant declaration, not a formulation disclosure.

What Must Appear in Section 3

• Chemical name and CAS number for every hazardous ingredient.
• Concentration or concentration range for each listed ingredient.
• Impurities and stabilisers that are themselves hazardous and affect classification.
• Relevant notes on the nature of the substances, such as reaction products or by-products.

How Concentrations Are Reported

Exact percentages are preferred, but concentration ranges are explicitly permitted. In EU practice, ranges follow the bands recommended in REACH Annex II guidance, such as “25–50%” or “10–25%”. In the US, OSHA permits ranges when the supplier makes a valid trade-secret claim, provided the range is narrow enough for a downstream user to complete their own assessments. Two warnings for buyers: first, a range is not a licence to hide a sensitizer — any ingredient contributing to classification must still be identified by name and CAS number. Second, when an SDS says only “proprietary flavor mixture” with no CAS numbers at all, you do not have a compliant Section 3 for the EU market.

Trade Secrets and Alternative Chemical Names

Trade secrecy is a real and lawful reason to withhold exact percentages, but it does not allow a supplier to hide a hazardous ingredient. Under OSHA, the identity of a hazardous ingredient may be withheld from the public SDS only if a valid trade-secret claim exists and the SDS still carries the required hazard information. Under CLP, a formulator can apply to ECHA for an alternative chemical name — a generic descriptor such as “fragrance mixture” or “reaction mass of terpenes” — that is valid for a limited, renewable period. The concentration data and the hazard classification must still be disclosed. If a flavor supplier refuses to provide any ingredient detail and cannot show a registered trade-secret claim, treat that as a compliance risk, not a legal shield.

Verifying Section 3 Against Your Own Records

The most powerful habit in flavor procurement is cross-checking Section 3 against the supplier technical datasheet and certificate of analysis. CAS numbers are the reliable key: the same aroma chemical is sold under many trade names, but its CAS registry number is unique. Check that every hazardous ingredient named in Section 3 appears in your allergen register, your restricted-substance screening, and — for US applicants — the ingredient statements in your PMTA flavor master files. A mismatch between the SDS and the master file is the fastest way to fail an FDA completeness review.

For the EU market, Section 3 data feeds directly into the poison centre notification process under CLP Article 45 and Annex VIII. The composition submitted in the notification must match the SDS concentration bands; discrepancies are routinely flagged by the member state appointed bodies that review notifications. When in doubt, request the confidential formulation sheet from your supplier under a non-disclosure agreement and reconcile it yourself.

SDS Section 3 Ingredient Composition for E-Liquid Flavors

A Ten-Point Audit Checklist for Sections 2 and 3

Use this checklist on every SDS before you approve a new flavor for your product line:

4. Confirm the SDS follows the 16-section GHS order and that the Section 2 and Section 3 headings match the GHS titles: “Hazard(s) identification” and “Composition/information on ingredients”.
5. Read the Section 2 classification and write out every H-code.
6. Verify each H-code maps to a hazard class and category that exists in your market regulation — OSHA HazCom in the US, CLP in the EU.
7. Check that the signal word matches the highest-severity category declared.
8. Confirm the pictograms are present and correspond to the declared classes.
9. Verify that P-codes cover prevention, response, storage, and disposal.
10. In Section 3, confirm that every named ingredient is either a hazardous ingredient or an impurity that affects classification.
11. Check every CAS number against an authoritative registry and against the supplier certificate of analysis.
12. Reconcile the concentration bands with the poison centre notification (EU) or the flavor master file (US).
13. Re-run the whole checklist whenever the supplier changes the formula or issues a new SDS revision.

A supplier that issues SDS revisions with clear version numbers and revision dates is a supplier that manages compliance as a process. A supplier that cannot produce a revision history is a risk.

Red Flags That Should Stop a Purchase

• Section 2 declares no hazards for a concentrate that is clearly flammable on the certificate of analysis.
• Section 3 lists no CAS numbers at all.
• Concentration data is missing for every ingredient.
• The SDS has no revision date and no version number.
• Hazard statements in Section 2 contradict Section 15 (regulatory information).
• The supplier cannot or will not share the SDS before sampling.

None of these red flags is an automatic disqualifier — some are fixable with a corrected SDS from the supplier. But each one is a reason to pause, ask questions, and document the answers.

How CUIGUAI Flavor Documents Its Concentrates

We treat Sections 2 and 3 as a discipline, not a formality. Every concentrate we release — from tobacco flavor concentrates to cooling flavor systems — ships with a GHS-compliant 16-section SDS that is regenerated from the actual formula rather than copied from a template. Classification is evaluated against the real mixture using CLP and HazCom rules, and Section 3 lists every hazard-relevant ingredient with its CAS number and concentration band.

If you are building a flavor library, ask for the SDS set before you sample. You should be able to read Section 2 and Section 3 of every concentrate before you ever open a bottle. That is the standard we hold ourselves to, and the standard your compliance team should hold every supplier to.

Frequently Asked Questions

What does Section 2 of an SDS contain?

Section 2, “Hazard(s) identification”, contains the classification of the substance or mixture, the label elements (signal word, pictograms, hazard statements H-codes, precautionary statements P-codes), and other hazards that do not result in classification.

What does Section 3 of an SDS contain?

Section 3, “Composition/information on ingredients”, lists the chemical identity, CAS number, and concentration or concentration range of each hazardous ingredient in a mixture, plus hazardous impurities and stabilisers that affect classification.

Do flavor SDSs have to list every ingredient?

No. Section 3 is required to list the ingredients that contribute to the classification of the mixture. Non-hazardous components and sub-threshold ingredients can be omitted, and trade-secret claims can protect exact percentages — but not the identity of hazardous components.

Why do Section 2 and Section 3 have to match?

Because classification is derived from composition. If the concentration data in Section 3 cannot produce the classification declared in Section 2, the document is technically incorrect and legally unreliable.

Is an SDS the same as a certificate of analysis?

No. A certificate of analysis documents batch-specific quality parameters such as assay, density, and purity. An SDS documents hazard information and is formulation-specific rather than batch-specific.

Flavor SDS Compliance Package for E-Liquid Brands

Talk to a Compliance Expert — or Request Free Flavor Samples

The CUIGUAI Flavor technical team supports e-liquid brands, importers, and compliance managers with SDS review, formulation documentation, and free development samples for qualifying projects.

📞 Phone: +86 0769 8838 0789
🌐 Website: https://www.cuiguai.com
📧 Email: info@cuiguai.com
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References

[1] Health and Safety Executive for Northern Ireland (HSENI), “REACH Safety Data Sheets”. https://www.hseni.gov.uk/reach-safety-data-sheets

[2] US Occupational Safety and Health Administration (OSHA), “Hazard Communication Standard: Safety Data Sheets”. https://www.osha.gov/hazcom/safety-data-sheets

[3] University of North Carolina at Chapel Hill, Environment Health and Safety, “Safety Data Sheets”. https://ehs.unc.edu/topic/safety-data-sheets/

[4] UC San Diego, “Understanding Safety Data Sheets”. https://blink.ucsd.edu/safety/resources/SDS/explained.html